Hi,
I have the impression that the application does not synchronize the two tracks correctly.
Are the grids of the 2 tracks aligned (that's what the SYNC does). If so, it means that one (maybe the two) grid is wrong.
The algorithm we use can make mistakes, that's why the beat-grid edit pane is here! Most of the time, if the grid is not correct, must be a down-beat calculation error. So:
1: grids aligned but you hear that the 2 songs are not in sync = edit the beat-grid
2: grids are not aligned after syncing = bug that we have never heard
loops are not perfectly shapes to the beat
Maybe related to the previous point?